Method of making a carburizing box with centrifugally cast side walls



NOV. 30, 1937. H, HARR|5 2,100,901

METHOD OF MAKING A CARBURIZING BOX WITH CENTRIFUGALLY CAST SIDE WALLS Fil ed May 17, 19:55

INVENTOR Hen ry H Harm's Patented Nov. 30, 1937 UNITED STATES PATENT OFFICE:

METHOD OF MAKING A CARBURIZING BOX WITH CENTRIFUGALLY CAST SIDE WALLS My invention relates to carburizing boxes, and particularly to carburizing boxes with centrifugally cast side walls.

Among the objects of the invention is the provision of a side wall member for carburizing boxes which is made highly dense and substantially free from porosity, by being subjected to the action of centrifugal force in the molten state and while being cooled, and hardened from such state.

Another object consists in the provision of a side-wall member for carburizing boxes made so non-porous and dense by centrifugal casting, and which is then flattened while hot, preferably on four sides, as to provide an integral polygonally-sectioned, preferably rectangular, side-wall member, which is nevertheless a continuous integral tube free from joints at the comers.

Another object consists in the casting of the tubular member, which can be cut into lengths to form side-wall members for carburizing boxes, with the molten material subject to centrifugal force, and with thickened parts constituting elemental or longitudinal parts of the completed tubular member, and which constitute the corners when the tube is flattened hot to form fiat wall portions, and by the corners being formed at these thickened portions, extra reenforcing material is provided for strengthening the box at the corners.

Other objects will appear from the following description of certain illustrative embodiments of the invention shown in the accompanying drawing, in whichgally cast tubular body which may be cut into lengths to form side walls of a round carburizing box;

Fig. 2 is a similar view of a modified form of centrifugally cast tubular body provided with thickened portions where corners will come when the intermediate parts are flattened to form side walls of a substantially rectangular box;

Fig. 3 is a section of the tube of Fig. 2 fiattened in parts to form side walls of a substantially rectangular box;

Fig. 4 is a vertical sectional view of a carburizing box having centrifugally east side walls and with an end welded in place, and said box set in a tray and containing carburizing compound and parts to be carburized, and

Fig. 5 is a view similar to part of Fig. 4 and showing a modified form of end or head.

Reference character Ill designates a centrifugally-cast round tubular member, and which Fig. 1 is a cross-sectional view of a centrifuby being cast in a, rotating mold is subjected in molten state to centrifugal force, whereby it is made dense and resistant to carbon penetration. The metal used is of a type adapted to stand up well under the conditions encountered in car- 5 burizing work at high temperatures, as for example a nickel-chromium-iron alloy is well adapted for such purpose, and the dense, close texture obtained by centrifugal casting enables longer useful carburizing box like to be obl0 tained with given proportions of the alloying metals, such as nickel and chromium, than when casting in the ordinary way. When the sidewall member for the carburizing box is to be round, the centrifugally cast tube ID for pro- 15 viding such side wall may be of uniform thickness as shown in Fig. l. In a modification, I may provide such a centrifugally cast tubular member Illa as shown in Fig. 2, with lengthwise-extending thickened portions l2, l2. In Fig. 2 I have shown four such thickened portions l2, arranged in'pairs, and by flattening the longer intermediate portions l4, M to form substantially fiat sides 5, and fiattening out the shorter intermediate portions I8, 25 ill to form substantially flat ends 20, 20 of a side wall member 22 shown in Fig. 3, a thickened wall part and strengthening effect is obtained at the corners, indicated at I2b, I211. The wall flattening may be performed on an elon- 3o gated tube and the tube then cut into lengths to form side walls for carburizing boxes of approximately the length indicated at 24, Fig. 4, or the centrifugally cast tubular member may first be cut into lengths, or originally made in lengths suitable for box walls and then sidefiattened, the metal being raised to a sufilciently high temperature, though well below the melting point, to permit the operation of flattening out the sides tobe performed without cracking or 40 breakage at the corners or elsewhere.

The heads may be made in various ways. Sheet material may be used, if desired, or cast heads 26 of metal similar to that usedfor the side walls, and same can be welded into place to 45 close one end of the box. In the form shown in Fig. 4 the cast head 28 comprises side walls or flanges 28 of substantially the same diameter as the side wall members and forming substantially continuations of said side walls of the box when welded thereto as indicated at 30. In Fig. 5 the head 26a is made somewhat larger so that the sidewall fiange 28a thereof encompasses the sidewall member of the box and same are welded to- 55 gether interiorly and exteriorly at 34 and 38 respectively. 4

For use, the boxes with closed end 26 down are usually loaded with pieces 38 to be carburized and carburizing compound 40, the tray 42 set on top, and the whole then inverted to the position shown in Fig. 4. The heads 26, 26a may be provided with feet 44, 44a if desired.

Further modifications within the scope of my claims are included within my invention.

I claim:

1. The process of making'a carburizing box which comprises the steps of centrifugally casting a long generally cylindrical tubular member, deforming the cylindrical tube while still hot into substantially prismatic shape, cutting ofl sections equal in length to the side walls desired for said carburizing box, and forming a separate head member corresponding in shape to the said side walls member, and thereafter welding said ,head to said member to close one end of said box.

2. Process as in claim 1 in which-extra material is added onto and cylindrical tube at spaced apart distances, and the tube is deformed between the points at which the extra material is added.

3. The process of making an integral cornerreenforced centrifugally cast side walls member made integral with the for a carburlzing box which consists in the steps of centrifugally casting a substantially round tubular member, adding extra amounts of material of which the box is made to said member thereby providing same with thickened portions extending lengthwise of the tubular member and thereafter flattening the tube walls between the thickened portions whereby same become reenforced corners of the complete side wall member.

4. The process of making a carburizing box having a centrifugally east side walls member which comprises the steps of centrifugally casting a substantially round tubular member, deforming the cylindrical tube into substantially rectangular shape, forming a head member with a floor portion and side walls corresponding in shape to the deformed tube walls, and thereafter welding said head to said walls to close one end of said box.

5. The process of claim 4 in which the side walls ofthe head comprise extensions to said tube walls.

6. The process of claim 4 in which the head corresponds in shape but not in size to the tube walls so that the tube walls fit into the head, and

are thereafter welded together.

HENRY H. HARRIS. 

